2. What effect does temperature have on the strength of a magnet?
1 answer:
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Answer :
(a) The first-order rate constant for the nuclear decay is,
(b) The fraction of 90-Sr that remains after 10 half-lives is,
(c) The time passed in years is, 127.4 years.
Explanation :
<u>Part (a) :</u>
Half-life = 28.1 years
First we have to calculate the rate constant, we use the formula :
Thus, the first-order rate constant for the nuclear decay is,
<u>Part (b) :</u>
Now we have to calculate the fraction of 90-Sr that remains after 10 half-lives.
Formula used :
where,
a = amount of reactant left after n-half lives
= Initial amount of the reactant
n = number of half lives = 10
Now put all the given values in the above formula, we get:
Thus, the fraction of 90-Sr that remains after 10 half-lives is,
<u>Part (c) :</u>
Now we have to calculate the time passed.
Expression for rate law for first order kinetics is given by:
where,
k = rate constant =
t = time passed by the sample = ?
a = let initial amount of the reactant = 100
a - x = amount left after decay process = 100 - 95.7 = 4.3
Now put all the given values in above equation, we get
Therefore, the time passed in years is, 127.4 years.